hasura/graphql-engine · warning · BooleanExpressionIssue::DataConnectorDoesNotSupportNestedObjectArrayFiltering

The data connector '{data_connector_name}' does not support

Error message

The data connector '{data_connector_name}' does not support filtering by nested object arrays. The comparable field '{field_name}' within {boolean_expression_type_name}' is of an object array type: {field_type}

What it means

Emitted when a comparable field inside a boolean expression type is an object array (array of objects) and the data connector backing the type does not support filtering by nested object arrays.

Source

Thrown at v3/crates/metadata-resolve/src/stages/boolean_expressions/types.rs:26

    types::error::ContextualError,
};
use graphql_types as ast;
use open_dds::models::ModelName;
use open_dds::{
    data_connector::{DataConnectorName, DataConnectorObjectType, DataConnectorOperatorName},
    relationships::RelationshipName,
    types::{CustomTypeName, FieldName, OperatorName},
};
use ref_cast::RefCast;
use serde::{Deserialize, Serialize};
use serde_with::serde_as;
use std::collections::{BTreeMap, BTreeSet};
use std::fmt::Display;
use std::sync::Arc;

#[derive(Debug, thiserror::Error, Clone, PartialEq, Eq)]
pub enum BooleanExpressionIssue {
    #[error(
        "The data connector '{data_connector_name}' does not support filtering by nested object arrays. The comparable field '{field_name}' within {boolean_expression_type_name}' is of an object array type: {field_type}"
    )]
    DataConnectorDoesNotSupportNestedObjectArrayFiltering {
        data_connector_name: Qualified<DataConnectorName>,
        boolean_expression_type_name: Qualified<CustomTypeName>,
        field_name: FieldName,
        field_type: QualifiedTypeReference,
    },
    #[error(
        "The data connector '{data_connector_name}' does not support filtering by nested scalar arrays. The comparable field '{field_name}' within '{boolean_expression_type_name}' is of a scalar array type: {field_type}"
    )]
    DataConnectorDoesNotSupportNestedScalarArrayFiltering {
        data_connector_name: Qualified<DataConnectorName>,
        boolean_expression_type_name: Qualified<CustomTypeName>,
        field_name: FieldName,
        field_type: QualifiedTypeReference,
    },
    #[error(

View on GitHub (pinned to 724551b9ae)

Solutions

Remove the object-array field from the boolean expression's comparable fields
Change the field's type to a scalar array or single object if filtering on it is not required
Use a data connector that supports nested object array filtering, if one exists for your source

Example fix

// before (HML)
types:
  Author:
    boolean_expression_type: AuthorFilter
    fields:
      articles: [Article]
        comparable: true      # object array -> error
// after
types:
  Author:
    boolean_expression_type: AuthorFilter
    fields:
      articles: [Article]
        comparable: false

Defensive patterns

Strategy: validation

Validate before calling

// Reject object-array comparable fields before resolve
for f in &be_type.comparable_fields {
    if let QualifiedType::Array(inner) = &f.field_type.underlying {
        if matches!(**inner, QualifiedType::Object(_)) {
            return Err(format!("{} is an object array; not filterable", f.name));
        }
    }
}

Type guard

fn is_object_array(t: &QualifiedTypeReference) -> bool {
    matches!(t.underlying(), QualifiedType::Array(inner) if matches!(**inner, QualifiedType::Object(_)))
}

Try / catch

if let BooleanExpressionIssue::DataConnectorDoesNotSupportNestedObjectArrayFiltering { field_name, .. } = &issue {
    log::warn!("skipping unfilterable field {field_name}");
}

Prevention

Only mark scalar/relationship fields as comparable
Check connector capability docs before adding array filters

When it happens

Trigger: Declaring a boolean expression type where a comparable field's QualifiedTypeReference resolves to an object array, while the resolved data connector lacks nested object array filter support.

Common situations: Marking a list-of-objects field as comparable (e.g. via `comparable: true` in Hasura ND HML); connectors like postgres-native that cannot push down nested array comparisons.

Related errors

AI-assisted analysis of hasura/graphql-engine@724551b9ae (2026-08-28). Data as JSON: /api/errors/f7810d6a248d3c75. Report an issue: GitHub.